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Contents
  1. 1. NSCharacterSet和NSMutableCharacterSet是用来表示一组Unicode字符
  2. 2. 常见系统的 字符集组合CharSet
  3. 3. 查找字符串中的一个字符 ‘.’
  4. 4. 去除一个NSArray中的重复元素
  5. 5. 截取一个NSArray的部分元素，同时去除重复元素
  6. 6. 将多个NSObject对象组装成NSOrderSet
  7. 7. 从NSOrderSet中查询某个元素
  8. 8. NSOrderSet遍历，以及去除重复元素的规则
  9. 9. NSOrderSet的集合运算
  10. 10. NSOrderSet过滤元素
  11. 11. 自定义创建NSCharacterSet
  12. 12. 判断 数字0 （字符编码为48）是否存在于 十进制数的字符集中
  13. 13. NSMutableCharacter的使用
  14. 14. 去除 两端 的空格
  15. 15. 通过数字把字符串变成数组
  16. 16. 过滤URL中的特殊字符
  17. 17. 去除单词中的 多余空格

NSCharacterSet和NSMutableCharacterSet是用来表示一组Unicode字符

常见系统的 字符集组合CharSet

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[NSCharacterSet alphanumericCharacterSet];          //所有数字和字母(大小写)  

[NSCharacterSet decimalDigitCharacterSet];          //0-9的数字  

[NSCharacterSet letterCharacterSet];                //所有字母  

[NSCharacterSet lowercaseLetterCharacterSet];       //小写字母  

[NSCharacterSet uppercaseLetterCharacterSet];       //大写字母  

[NSCharacterSet punctuationCharacterSet];           //标点符号  

[NSCharacterSet whitespaceAndNewlineCharacterSet];  //空格和换行符  

[NSCharacterSet whitespaceCharacterSet];            //空格

还有很多iOS7之后新添加的

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@interface NSCharacterSet (NSURLUtilities)

// Predefined character sets for the six URL components and subcomponents which allow percent encoding. These character sets are passed to -stringByAddingPercentEncodingWithAllowedCharacters:.

// Returns a character set containing the characters allowed in an URL's user subcomponent.
+ (NSCharacterSet *)URLUserAllowedCharacterSet NS_AVAILABLE(10_9, 7_0);

// Returns a character set containing the characters allowed in an URL's password subcomponent.
+ (NSCharacterSet *)URLPasswordAllowedCharacterSet NS_AVAILABLE(10_9, 7_0);

// Returns a character set containing the characters allowed in an URL's host subcomponent.
+ (NSCharacterSet *)URLHostAllowedCharacterSet NS_AVAILABLE(10_9, 7_0);

// Returns a character set containing the characters allowed in an URL's path component. ';' is a legal path character, but it is recommended that it be percent-encoded for best compatibility with NSURL (-stringByAddingPercentEncodingWithAllowedCharacters: will percent-encode any ';' characters if you pass the URLPathAllowedCharacterSet).
+ (NSCharacterSet *)URLPathAllowedCharacterSet NS_AVAILABLE(10_9, 7_0);

// Returns a character set containing the characters allowed in an URL's query component.
+ (NSCharacterSet *)URLQueryAllowedCharacterSet NS_AVAILABLE(10_9, 7_0);

// Returns a character set containing the characters allowed in an URL's fragment component.
+ (NSCharacterSet *)URLFragmentAllowedCharacterSet NS_AVAILABLE(10_9, 7_0);

@end

查找字符串中的一个字符 ‘.’

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NSCharacterSet *set = [NSCharacterSet characterSetWithRange:NSMakeRange('.', 1)];

NSString *str = @"dawd.awdawdwdawd.dawd";

NSRange range = [str rangeOfCharacterFromSet:set];

去除一个NSArray中的重复元素

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NSOrderedSet *set1 = [NSOrderedSet orderedSetWithArray:@[@3,@7,@3,@3,@0]];
NSLog(@"%@",set1);
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输出结果:

{(
3,
7,
0
)}

截取一个NSArray的部分元素，同时去除重复元素

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NSArray *array = @[@3,@7,@3,@3,@0];
NSOrderedSet *set2 = [NSOrderedSet orderedSetWithArray:array range:NSMakeRange(0, 4) copyItems:NO];
NSLog(@"%@",set2);
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输出结果:

{(
3,
7
)}

将多个NSObject对象组装成NSOrderSet

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NSOrderedSet *set3 = [NSOrderedSet orderedSetWithObjects:@"aaaa",@4, nil];
NSLog(@"%@",set3);
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输出结果:

{(
aaaa,
4
)}

从NSOrderSet中查询某个元素

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NSOrderedSet *set1 = [NSOrderedSet orderedSetWithArray:@[@3,@7,@3,@3,@0]];
NSLog(@"%@",set1);

if ([set1 containsObject:@3]) {
NSLog(@"EXIST");
}
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输出结果:

{(
3,
7,
0
)}

EXIST

NSOrderSet遍历，以及去除重复元素的规则

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NSOrderedSet *set1 = [NSOrderedSet orderedSetWithArray:@[@3,@7,@3,@3,@0]];

[set1 enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
NSLog(@"obj = %@， idx = %ld", obj, idx);

}];
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输出结果:

obj = 3， idx = 0
obj = 7， idx = 1
obj = 0， idx = 2

NSOrderSet的集合运算

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NSOrderedSet *set1 = [NSOrderedSet orderedSetWithObjects:@4,@5,@6,@7,nil];

NSMutableOrderedSet *set2 = [NSMutableOrderedSet orderedSetWithObjects:@8,@9,@10, nil];

//判断 set1中是否存在至少一个元素，是否存在于set2中
if ([set1 intersectsOrderedSet:set2]) {
NSLog(@"intersectsOrderedSet -- yes");
}

//判断 set1中所有元素，是否存在于set2中（是否是字串）
if ([set1 isSubsetOfOrderedSet:set2]) {
NSLog(@"isSubsetOfOrderedSet -- yes");
}

//合并两个order set
//可变set主动合并
[set2 unionOrderedSet:set1];
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输出结果:

{(
8,
9,
10,
4,
5,
6,
7
)}

NSOrderSet过滤元素

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NSOrderedSet *set = [NSOrderedSet orderedSetWithObjects:@3,@1,@8,@6,@12, nil];

NSIndexSet *indexs = [set indexesOfObjectsWithOptions:NSEnumerationConcurrent
passingTest:^BOOL(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop)
{
//返回YES，当前遍历元素会被添加到NSIndexSet
//返回NO，被过滤掉

if ([obj integerValue] >= 6) {
return YES;
} else {
return NO;
}
}];

NSArray *valueArray = [set objectsAtIndexes:indexs];

NSLog(@"%@",valueArray);
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输出结果:

(
8,
6,
12
)

自定义创建NSCharacterSet

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使用给定的字符串组成一个CharSet

[NSCharacterSet characterSetWithCharactersInString:@"Hello"];

判断 数字0 （字符编码为48）是否存在于 十进制数的字符集中

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//1. 十进制数字的字符集
[NSCharacterSet alphanumericCharacterSet]

//2. 判断数字0是否存在于字符集
BOOL isExist = [charSet characterIsMember:48];

NSMutableCharacter的使用

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NSMutableCharacterSet *set1 = [NSMutableCharacterSet characterSetWithCharactersInString:@"Hell"];  
NSMutableCharacterSet *set2 = [NSMutableCharacterSet characterSetWithCharactersInString:@"ello"];  

//去掉某些字符  
[set2 removeCharactersInString:@"e"]; //--->l, o  

//加上某些字符  
[set2 addCharactersInString:@"e"];    //--->e, l, o  

//set相加  
[set2 formUnionWithCharacterSet:set1]; //--->H,e,l,o  

//本身加上另外一个的set相交  
[set2 formIntersectionWithCharacterSet:set1]; //--->H,e,l   

//除以包含的以外的set  
[set2 invert];

去除 两端 的空格

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//1. 空格的字符集
NSCharacterSet *whiteSpaceSet = [NSCharacterSet whitespaceCharacterSet];

//2. 去除字符集中的字符
[@"  aaa   " stringByTrimmingCharactersInSet: whiteSpaceSet];

通过数字把字符串变成数组

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[@"a1aa2aaa3aaaa4aaaaa" componentsSeparatedByCharactersInSet:[NSCharacterSet decimalDigitCharacterSet]];

过滤URL中的特殊字符

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static NSString * AFPercentEscapedStringFromString(NSString *string) {

//对URL中包含的特殊字符（:#[]@）替换成 %
// does not include "?" or "/" due to RFC 3986 - Section 3.4
static NSString * const kAFCharactersGeneralDelimitersToEncode = @":#[]@";

static NSString * const kAFCharactersSubDelimitersToEncode = @"!$&'()*+,;=";

//创建一个用于URL的字符集
NSMutableCharacterSet * allowedCharacterSet = [[NSCharacterSet URLQueryAllowedCharacterSet] mutableCopy];

//:#[]@ + !$&'()*+,;=
NSString *temp = [kAFCharactersGeneralDelimitersToEncode stringByAppendingString:kAFCharactersSubDelimitersToEncode];

//从字符集中移除上面的所有 特殊字符
[allowedCharacterSet removeCharactersInString:temp];

// FIXME: https://github.com/AFNetworking/AFNetworking/pull/3028
// return [string stringByAddingPercentEncodingWithAllowedCharacters:allowedCharacterSet];

//下面是从传入的string中
static NSUInteger const batchSize = 50;

NSUInteger index = 0;
NSMutableString *escaped = @"".mutableCopy;

while (index < string.length) {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wgnu"
NSUInteger length = MIN(string.length - index, batchSize);
#pragma GCC diagnostic pop
NSRange range = NSMakeRange(index, length);

// To avoid breaking up character sequences such as 👴🏻👮🏽
range = [string rangeOfComposedCharacterSequencesForRange:range];

NSString *substring = [string substringWithRange:range];

//从substring中 替换掉 不存在于allowedCharacterSet字符集中的 其他字符
NSString *encoded = [substring stringByAddingPercentEncodingWithAllowedCharacters:allowedCharacterSet];

[escaped appendString:encoded];

index += range.length;
}

return escaped;
}

去除单词中的 多余空格

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@"  My     name    is     Johnny!  "

变成

@"My name is Johnny!"

实现代码如下，主要使用NSCharSet + NSPredicate + 数组截取、过滤、拼接

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NSString *exampleStr = @"   My    name    is    Johnny!     ";

//1. 去掉两端的空格
exampleStr = [exampleStr stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

//2. 然后以空格字符集截取成数组（很多空格也被截取成一个数组元素）
NSArray *exampleArr = [exampleStr componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

//3. 创建一个过滤条件: 不等于空字符
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"self <> ''"];

//4. 数组过滤掉空格字符的元素
exampleArr = [exampleArr filteredArrayUsingPredicate:predicate];

//5. 数组组装成字符串
exampleStr = [exampleArr componentsJoinedByString:@" "];
Contents
  1. 1. NSCharacterSet和NSMutableCharacterSet是用来表示一组Unicode字符
  2. 2. 常见系统的 字符集组合CharSet
  3. 3. 查找字符串中的一个字符 ‘.’
  4. 4. 去除一个NSArray中的重复元素
  5. 5. 截取一个NSArray的部分元素，同时去除重复元素
  6. 6. 将多个NSObject对象组装成NSOrderSet
  7. 7. 从NSOrderSet中查询某个元素
  8. 8. NSOrderSet遍历，以及去除重复元素的规则
  9. 9. NSOrderSet的集合运算
  10. 10. NSOrderSet过滤元素
  11. 11. 自定义创建NSCharacterSet
  12. 12. 判断 数字0 （字符编码为48）是否存在于 十进制数的字符集中
  13. 13. NSMutableCharacter的使用
  14. 14. 去除 两端 的空格
  15. 15. 通过数字把字符串变成数组
  16. 16. 过滤URL中的特殊字符
  17. 17. 去除单词中的 多余空格